The present invention relates to surgical blades and, more particularly, to endoscopic surgical blades having elongate, inner and outer tubular members with distal ends cooperating to cut or resect bodily tissue.
Endoscopic surgical blades typically have an elongate outer tubular member terminating at a distal end having an opening in the side wall and/or the end wall to form a cutting port or window and an elongate inner tubular member coaxially disposed in the outer tubular member and having a distal end disposed adjacent the opening in the distal end of the outer tubular member. The distal end of the inner tubular member has a surface or edge for engaging tissue via the opening in the distal end of the outer tubular member and in many cases cooperates with the opening to shear or cut tissue. The inner tubular member is typically rotatable relative to the outer tubular member.
The distal end of the inner tubular member can have various configurations dependent upon the surgical procedure to be performed. The opening in the distal end of the outer tubular member is configured to cooperate with the particular configurations of the distal end of the inner tubular member. For example, the inner and outer tubular members can be configured to produce whisker cutting, synovial resection, arthroplasty burring or abrading, side cutting, meniscus cutting, trimming, full radius resection, end cutting and the like, and the various configurations are referred to herein generically as xe2x80x9ccutting blades or edges.xe2x80x9d Cut tissue is typically aspirated through the lumen of the inner tubular member.
The inner and outer members are typically formed from electropolished stainless steel. It is known to coat the surfaces of the members with a layer of silver, gold, tin-nickel alloy, or titanium nitride to act as a bearing surface between the outer and inner members.
According to one aspect of the invention, a surgical blade includes an elongate outer tubular member and an elongate inner member movably received within the outer member. The inner member has a distal cutter positionable adjacent a distal opening in the outer member. A coating from the group consisting of copper and alloys or mixtures of copper and one or more other elements is on a portion of the outer surface of the inner member, the inner surface of the outer member, or both.
Embodiments of this aspect of the invention may include one or more of the following features.
The coating is white bronze, an alloy of copper, tin and zinc. Preferably about 55-60% copper, 20-25% tin, and 15-20% zinc. The outer and inner members are formed from stainless steel, e.g, soft stainless steel such as 300 series stainless steel.
The coating is in a region of the distal opening of the outer tubular member, a region of the distal cutter of the inner member, or both. The coating is along substantially an entire length of the inner surface of the outer tubular member, the outer surface of the inner member, or both.
The inner member defines a lumen. The inner member is received within the outer tubular member for rotation therein. Alternatively, the inner member is received within the outer tubular member for axial, reciprocating motion therein.
The clearance between a distal region of the outer member and a distal region of the inner member prior to applying the coating is in a range of about 0.0001xe2x80x3 to 0.002xe2x80x3, preferably about 0.00075xe2x80x3 to 0.00175xe2x80x3. The thickness of the coating is in a range of about 0.00002xe2x80x3 to 0.0005xe2x80x3.
According to another aspect of the invention, a method of cutting tissue includes providing a cutting blade having a portion of the outer surface of the inner member, the inner surface of the outer members, or both coated with a coating from the group consisting of copper and alloys or mixtures of copper and one or more other elements, placing the cutting blade against the tissue, and driving the inner member to cut the tissue.
Embodiments of this aspect of the invention may include one or more of the following features.
The outer and inner members are formed from stainless steel, e.g., soft stainless steel. The clearance between a distal region of the outer member and a distal region of the inner member prior to applying the coating is in a range of about 0.0001xe2x80x3 to 0.002xe2x80x3, preferably about 0.00075xe2x80x3 to 0.00175xe2x80x3. The coating has a thickness in a range of about 0.00002xe2x80x3 to 0.0005xe2x80x3. The method includes cutting hard tissue such as bone. The step of driving includes rotating the inner member within the outer member. The blade is sterilizable by autoclaving.
According to another aspect of the invention, a method of making a surgical blade includes providing the outer tubular member and the inner member, and coating the inner surface of the outer tubular member, the outer surface of the inner tubular member, or both with copper or alloys or mixtures of copper and one or more other elements.
Advantages of the invention may include one or more of the following: The copper or copper alloy coating limits shedding. The coating provides good performance of the surgical blade particularly at high speeds, and also provides good performance of the surgical blade under high loads, e.g., when cutting bone. The coating is available in alloys which have oxidation resistant properties to limit tarnishing. The coating can be deposited by conventional electroplating techniques in an economical manner, can be sterilized by conventional processing such as gamma radiation and autoclaving, without changing color, and is non-cytotoxic.
Other features and advantages of the invention will be apparent from the following detailed description.